Steel



Patented July 23, 1929.

UNITED STATES 1,721,555 PATENT OFFICE.

WINFIELD C. HAMILTON AND CLARENCE E. SIMS, CHICAGO, ILLINOIS, ASSIGNORS'IO AMERICAN STEEL FOUNDRIES, OF CHICAGO, ILLINOIS, A CORPORATION 01'NEW JERSEY.

STEEL.

No Drawing.

This invention relates to an improved steel and particularly to animproved high manganese pearlitic steel.

The steel contemplated in this invention is 5 found to have varioussuperior qualities and properties, and may be used in many applicationswhere its properties are found desirable, but it is found that it hasparticular usefulness when applied to the manufacture of railroad carwheels.

One of the advantages realized in this improved steel is that it hasgreater hardness penetration as affected by the hardening process, suchas by quenching with water, oil, or

other suitable mediums. This quality makes for a greater depth ofhardened surface on articles made from this improved steel andconsequently is very advantageous when applied to car wheels in that itis best to provide a hard wearing surface for a greater depth inwardlyof the outer periphery and thereby increase the life of the wheel inservice. It is to be understood, however, that wherever greater hardnesspenetration makes for improvement that this steel will be applicablewith more improved results.

Another advantage realized in this improved steel is that it is moreresistant to subsequent tempering or drawing temperatures, or, in otherwords, is a steel, the hardness of which is less affected than otherpearlitic steels heretofore known when they are subsequently heattreated in a manner to temper them or reduce their brittleness. Thisfeature makes for improvement particularly in the case of car wheels inthat the hardness of the wearing surfaces is little affected when thearticles are tempered by subsequent heat treatment and also particularlyin that the heating of the wheel rim in service, due to brakeapplication, which frequently reaches 800 or 900 F., does not affect toa great extent the hardness of the metal whereby the wheel is moreresistant to the wear and tear of the track and brake shoes at thesehigh temperatures.

In practice it is well known that car wheels disintegrate and thatparticles of the wheel tread crack and splinter away from the main bodyof the wheel due to the unusually severe conditions to which Wheels aresubjected in service. In many well known types of wheels this ispartially attributable to the softening of the Wheel surface under theheat created by friction between the parts, and particu- Serial No.237,584.

larly the brakeshoe on the wheel surface. Where this occurs the yieldpoint of the steel materially decreases and therefore the steel is moresubject to fatigue cracks. In the present steel, even though the heat bepresent, it has very little softening effect on the metal andconsequently the disadvantages heretofore realized in this particularare to a large extent eliminated.

The present advantages are found to exist in a steel known in the art asa high manganese pearlitic steel in which 50% to 2.00% of chromium ispresent. It is to be understood that thehigh manganese pearlitic steelmay vary within certain limits as to its constituent parts, the mainrequirement being that it contain suflic-ient manganese to classify itas a high manganese steel and have the other constituents so selectedand proportioned relative to the manganese content and the subsequentheat treatment that the steel formed be what is known in the art as ahigh manganese pearlitic steel. It has been found that the highmanganese pearlitic steel might, if desired, be high in silicon, butthis is not an essential part of the present invention. It is found, bywayof illustration, that this invention may be practiced with a highdegree of success when the steel is made containing the followingsubstances in the proportions specified:

Percent. Manganese 1.00 to 2.50 Carbon .20 to .60 Silicon .20 to 1.50Chromium .50 to 2.00

Balance, iron and a small amount of other substances occurring asimpurities.

The chromium may be supplied and added to the metal in any form which isdesired, it only being necessary to assure that the final product hasthe proper chromium content, but for the purpose of illustration it ispreferred to add the chromium in the form of ferro-chromium. a wellknown form of which contains approximately of chromium.

It has been found in practice that the high manganese steel of the abovecharacter, having the specific amount of chromium as a constituent,possesses the properties above enumerated and that an especiallyimprovedsteel is produced.

To illustrate the hardness penetration, which hardness is less affectedby subsequent drawing or heating to comparatively low temperatures, theapplicants have conducted a simple test given below, which conclusivelyshows the advantages of this invention.

Two high manganese pearlitic steels Were taken, one with no chromium andone with chromium present. Bars one inch square and six inches long wereheated slightly above the upper critical temperature and then the endswere immersed to a depth of one inch until the bars were cool. TheBrinnell hardness nmnbers were then taken, after which the bars wereheated or drawn at 850 F. for sixteen hours. The Brinnell hardnessnumbers were again taken. The following results were obtained bysuch'test:

Attention is further directed to the fact that the steel hereindescribed has such properties that it lends itself peculiarly withextraordinary advantage to the manufacture of car wheels in that theproperties which are realized in this steel answers so satisfactorilythe problems which are encountered in steel failures in ear wheels inservice.

It will be readily appreciated from the above description that we havenot only made animproved steel, which may be used for any purpose whereits properties are desirable, but that we have also provided an improvedcar wheel which is capable of longer life and better service and onewhich is free from the main disadvantages heretofore encountered.

It is to be further understood that this steel, whether it be applied tocar wheels or other articles, serves equally well, whether the articlebe cast or made by a forging, rolling, or other ope 'ation.

lVe claim: u

l. A car wheel composed of a high manganese pearlitic steel containingchromium in the quantity of from 50% to 2.00%.

2. A car wheel composed of high manganese pearlitie steel, containingmanganese in the quantity of from 1.00% to 2.50% and chromium of from50% to 2.00%.

3. A cast car wheel composed of a high manganese pearlitic steelcontaining chromium in the quantity of from .5070 to 2.0070. 1

l. A cast car wheel composed of high manganese pearlitic steel,containing manganese in the quantity of from 1.00% to 2.50 7 andchromium of from .50% to 2.00%.

Signed at Indiana. Harbor, Indiana, this 29th day of November, 1927.

VVINFIELD C. HAMILTON. CLARENCE E. SIMS.

